Method for performing a photolithography process

ABSTRACT

A method for performing a photolithography process is provided. The method includes forming a resist layer over a substrate and exposing a portion of the resist layer to form an exposed region and an unexposed region by performing an exposure process. The method includes performing a baking process on the resist layer, so that voids are formed in the exposed region of the resist layer. The method also includes removing the unexposed region of the resist layer to form a recess in the resist layer and filling a post treatment coating material in the recess and the void. The method further includes removing a portion of the post treatment coating material by performing a second develop process, and another portion of the post treatment coating material is left on surfaces of the exposed region of the resist layer to form a patterned resist layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This Application claims the benefit of U.S. Provisional Application No.62/555,872 filed on Sep. 8, 2017, and entitled “Method for performing aphotolithography process with post treatment”, the entirety of which isincorporated by reference herein.

BACKGROUND

Semiconductor devices are used in a variety of electronic applications,such as personal computers, cell phones, digital cameras, and otherelectronic equipment. Semiconductor devices are typically fabricated bysequentially depositing insulating or dielectric layers, conductivelayers, and semiconductive layers of material over a semiconductorsubstrate, and patterning the various material layers using lithographyto form circuit components and elements thereon. Many integratedcircuits are typically manufactured on a single semiconductor wafer, andindividual dies on the wafer are singulated by sawing between theintegrated circuits along a scribe line. The individual dies aretypically packaged separately, in multi-chip modules, for example, or inother types of packaging.

Lithography processes are extensively utilized in integrated circuit(IC) manufacturing, and various IC patterns are transferred to aworkpiece to form an IC device. Since feature sizes continue todecrease, fabrication processes continue to become more difficult toperform. Accordingly, although existing lithography techniques have beengenerally adequate for their intended purposes, they have not beenentirely satisfactory in all respects.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It shouldbe noted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIGS. 1A-1I show cross-sectional representations of various stages ofperforming a photolithography process, in accordance with someembodiments of the disclosure.

FIG. 2A shows a diagrammatical view of a chemical structure of theresist layer, in accordance with some embodiments.

FIGS. 2B and 2C show chemical structures of an exemplary ALG, inaccordance with some embodiments.

FIG. 2D shows a schematic diagram that shows a reaction occurring in aresist layer when the exposure process is performed in aphotolithography process, in accordance with some embodiments.

FIG. 2E shows a schematic diagram that shows the arrangement of thepolymer of the resist layer and the first post treatment coatingmaterial, in accordance with some embodiments.

FIGS. 3A-3H show cross-sectional representations of various stages ofperforming a photolithography process, in accordance with someembodiments of the disclosure.

FIG. 3E′ shows a cross-sectional representation of the exposed region ofthe resist layer, in accordance with some embodiments of the disclosure.

FIGS. 4A-4G show cross-sectional representations of various stages ofperforming a photolithography process, in accordance with someembodiments of the disclosure.

FIG. 4G′ shows cross-sectional representations of the exposed region ofthe resist layer, in accordance with some embodiments of the disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the subject matterprovided. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,so that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Some variations of the embodiments are described. Throughout the variousviews and illustrative embodiments, like reference numbers are used todesignate like elements. It should be understood that additionaloperations can be provided before, during, and after the method, andsome of the operations described can be replaced or eliminated for otherembodiments of the method.

Embodiments for a semiconductor structure and method for forming thesame are provided. FIGS. 1A-1I show cross-sectional representations ofvarious stages of performing a photolithography process, in accordancewith some embodiments of the disclosure. In some embodiments, thephotolithography process is used in a negative tone development (NTD)process. “Negative tone development (NTD) processes” have been used topattern material layers. The resist layer is exposed by a light source,followed by post-exposure baking. A portion of the composition of theexposed region of the resist layer is changed, and it is more difficultto dissolve this portion in the NTD solvent. When the resist layer isdeveloped, only the unexposed region of the resist layer is washed away.

Referring to FIG. 1A, a substrate 102 is provided. The substrate 102 maybe made of silicon or another semiconductor material. In someembodiments, the substrate 102 is a wafer. Alternatively oradditionally, the substrate 102 may include other elementarysemiconductor materials such as germanium. In some embodiments, thesubstrate 102 is made of a compound semiconductor or alloysemiconductor, such as silicon carbide, gallium arsenic, indiumarsenide, or indium phosphide, silicon germanium, silicon germaniumcarbide, gallium arsenic phosphide, or gallium indium phosphide. In someembodiments, the substrate 102 includes an epitaxial layer. For example,the substrate 102 has an epitaxial layer overlying a bulk semiconductor.

Some device elements may be formed over the substrate 102. Examples ofsuch device elements include transistors (e.g., metal oxidesemiconductor field effect transistors (MOSFET), complementary metaloxide semiconductor (CMOS) transistors, bipolar junction transistors(BJT), high-voltage transistors, high-frequency transistors, p-channeland/or n channel field effect transistors (PFETs/NFETs), etc.), diodes,and other applicable elements. Various processes are performed to formdevice elements, such as deposition, etching, implantation,photolithography, annealing, and other applicable processes.

The substrate 102 may include various doped regions such as p-type wellsor n-type wells). Doped regions may be doped with p-type dopants, suchas boron or BF₂, and/or n-type dopants, such as phosphorus (P) orarsenic (As). In some other embodiments, the doped regions may be formeddirectly on the substrate 102.

The substrate 102 also includes isolation structures (not shown). Theisolation structure is used to define and electrically isolate variousdevices formed in and/or over the substrate 102. In some embodiments,the isolation structure includes shallow trench isolation (STI)structure, local oxidation of silicon (LOCOS) structure, or anotherapplicable isolation structure. In some embodiments, the isolationstructure includes silicon oxide, silicon nitride, silicon oxynitride,fluoride-doped silicate glass (FSG), or another suitable material.

Next, a material layer 104 is formed over the substrate 102. Thematerial layer 104 is configured to be patterned or doped in subsequentmanufacturing processes. The material layer 104 may be one or morematerial layers. In some embodiments, the material layer 104 includes asilicon layer, a dielectric layer, and/or a doped poly-silicon layer.

Afterwards, as shown in FIG. 1B, a bottom layer 106 is formed over thematerial layer 104, in accordance with some embodiments of thedisclosure. The bottom layer 106 may be a first layer of a tri-layerresist layer (also referred to as tri-layer photoresist). The bottomlayer 106 may contain a material that is patternable and/or haveanti-reflection properties. In some embodiments, the bottom layer 106 isa bottom anti-reflective coating (BARC) layer. In some embodiments, thebottom layer 106 includes a carbon backbone polymer. In someembodiments, the bottom layer 106 is made of a silicon-free material. Insome embodiments, the bottom layer 106 is formed by a spin-on coatingprocess, a chemical vapor deposition process (CVD), a physical vapordeposition (PVD) process, or another suitable deposition process.

A middle layer 108 is formed over the bottom layer 106. The middle layer108 may have a composition that provides anti-reflective propertiesand/or hard mask properties for the photolithography process. Inaddition, the middle layer 108 is designed to provide etchingselectivity from the bottom layer 106 and a resist layer 110. In someembodiments, the middle layer 108 is made of silicon nitride, siliconoxynitride or silicon oxide.

A resist layer 110 is formed over the middle layer 108. The resist layer110 may be positive photoresist or negative photoresist. In someembodiments, the top layer 110 includes a carbon backbone polymer. Insome embodiments, the resist layer 110 is a chemical amplified (CA)resist. In some embodiments, the resist layer 110 is made of Poly(methyl methacrylate) (PMMA), Poly (methyl glutarimide) (PMGI), Phenolformaldehyde resin (DNQ/Novolac), SU-8 or another applicable material.The resist layer 110 further includes a photo-acid generator (PAG). Whenthe resist layer 110 is exposed to radiation (e.g. light), the PAG formsa small amount of acid. The PAG may have a concentration ranging betweenabout 1% and 30% of the weight of the resist layer 110.

Afterwards, as shown in FIG. 1C, a mask 10 is formed over the resistlayer 110, and an exposure process 12 is performed on the resist layer110, in accordance with some embodiments of the disclosure. As a result,an exposed region 110 a and an unexposed region 110 b are formed.

In some embodiments, a negative tone developer (NTD) process isperformed, the exposed region 110 a of the resist layer 110 remains, andthe unexposed region 110 b of the resist layer 110 is removed by thefirst developer.

The radiation energy of the exposure process 12 may include a 248 nmbeam by Krypton Fluoride (KrF) excimer lasers, a 193 nm beam by ArgonFluoride (ArF) excimer lasers, a 157 nm beam by Fluoride (F2) ExcimerLasers, or Extreme ultra-violet (EUV) light, such as EUV light withwavelength of about 13.5 nm.

Afterwards, as shown in FIG. 1D, the resist layer 110 is developed byperforming a first develop process to form a patterned top layer 110 a,in accordance with some embodiments of the disclosure. A portion of theresist layer 110 is removed by the first developer. The exposed region110 a of the resist layer 110 is left and the unexposed region 110 a ofthe resist layer 110 is removed by the first developer. A recess 111 isformed between two adjacent exposed regions 110 a of the resist layer110.

The first developer may be an organic solvent. In some embodiments, thefirst developer includes methyl amyl ketone (MAK), n-butyl acetate(nBA), n-pentylacetate (nPA), ethyl amyl ketone (EAK), or a combinationthereof.

FIG. 2A shows a diagrammatical view of a chemical structure of theresist layer 110, in accordance with some embodiments. FIGS. 2B and 2Cshow chemical structures of an exemplary ALG, in accordance with someembodiments.

As shown in FIG. 2A, the resist layer 110 includes a polymer 30, an acidlabile group (ALG) 40 and a photoacid generator (PAG) 50. The PAG 50generates acid when the resist layer 110 is exposed to the radiationenergy and absorbs the radiation. The acid labile group (ALG) 40 cleavesfrom the polymer 30 when the resist layer 110 is in the acidicenvironment. In other words, the PAG 50 catalyzes cleaving of ALG 40from the polymer 30 when the resist layer 110 is exposed to radiation.As a result, the polarity and/or solubility of the exposed region 110 aof the resist layer 110 is changed.

In embodiments as shown in FIG. 2B, the ALG 40 is methlycyclopentyl(MCP) bonded to a carboxyl group of the polymer 30 by covalent bonding.In embodiments as shown in FIG. 2C, the ALG 40 is ethylcyclopentylbonded to a carboxyl group of the polymer 30 by covalent bonding.

In some embodiments, the PAG 50 includes a fluorine-containingfunctional group, such as perfluorosulfonate, diphenyliodoniumtrifluoromethane sulfonate, diphenyliodonium nonafluorobutane sulfonate,triphenylsulfonium trifluromethane sulfonate, triphenylsulfoniumnonafluorobutane sulfonate, triphenylsulfoniumbis(perfluoromethanesulfonyl) imide, fluorine-containing functionalgroup, or a combination thereof. In some implementations, PAG 50includes a phenyl ring based functional group, a heterocyclic ring basedfunctional group, other suitable functional group, or a combinationthereof.

FIG. 2D shows a schematic diagram that shows a reaction occurring in aresist layer 110 when the exposure process 12 is performed on the resistlayer 110, in accordance with some embodiments.

As shown in FIG. 2D, after the ALG 40 is released from the polymer 30 ofthe resist layer 110, the carboxylic acid group is formed in the polymer30. After the exposing process, a post-exposure-baking (PEB) process isperformed on the resist layer 110. The leaving ALG 40 will be releasedinto the air during baking or rinsed away during the first developprocess (performed later). As a result, some voids 112 (shown in FIG.1D) are formed in the exposed region 110 a of the resist layer 110 sincethe PEB process or the first develop process produces outgassing of theacid labile group (ALG) 40.

In some embodiments, the PEB process is performed at a temperature in arange from about 80 degrees to about 160 degrees. In some embodiments,the PEB process is performed for a period of time ranging from about 5seconds to about 60 seconds.

Next, as shown in FIG. 1E, a first post treatment coating material 120is formed in the recess 111 and the voids 112, and over the surfaces ofthe exposed region 110 a of the resist layer 110, in accordance withsome embodiments. More specifically, the first post treatment coatingmaterial 120 covers the top surface and sidewall surfaces of the exposedregion 110 a of the resist layer 110. Since the first post treatmentcoating material 120 is in liquid form, it flows into the voids 112 ofthe exposed region 110 a of the resist layer 110.

The first post treatment coating material 120 is configured to repairthe voids 112 and prevent pattern collapse. In addition, the first posttreatment coating material 120 is configured to improve the surfaceroughness of the resist layer 110. Therefore, the line width roughness(LWR) of the exposed region 110 a of the resist layer 110 is improved.

In some embodiments, a post treatment process is performed on the firstpost treatment coating material 120 after forming the first posttreatment coating material 120 and before removing a portion of the posttreatment coating material. The post treatment process is configured toseed up the outgassing of the solvent in the first post treatmentcoating material 120. The post treatment process includes a radiationcuring process, a thermal baking process or a combination thereof. Insome embodiments, the post treatment process is performed at atemperature in a range from about 80 degrees to about 160 degrees. Insome embodiments, the post treatment process is performed for a periodof time ranging from about 60 seconds to about 120 seconds.

FIG. 2E shows a schematic diagram that shows the arrangement of thepolymer 30 of the resist layer 110 and the first post treatment coatingmaterial 120, in accordance with some embodiments.

As shown in FIG. 2E, the first post treatment coating material 120includes a first segment 22 and a second segment 24 linked to the firstsegment 22. In some other embodiments, the first post treatment coatingmaterial 120 further includes a third segment 26 liked to the secondsegment 24.

The first segment 22 (labeled as “A”) is configured to form a physicalbond or a chemical bond with the exposed region 110 a of the resistlayer 110. The first segment 22 (labeled as “A”) includes a halogenatom, hydroxy group, amine group, sulfo group, or carboxyl group. Insome embodiments, the first segment 22 is an amine group.

The second segment 24 (labeled as “B”) is configured to increase theetching resistance of the first post treatment coating material 120. Thesecond segment 24 (labeled as “B”) includes substituted or unsubstitutedlinear, branched, or cyclic hydrocarbon group, or substituted orunsubstituted aromatic group, and/or at least one hydrogen of theunsubstituted linear, branched, or cyclic hydrocarbon group issubstituted by halogen, hydroxyl, sulfo or carboxyl. In someembodiments, the second segment 22 is substituted or unsubstitutedC3-C10 alkylene. In some embodiments, the second segment 22 isphenylene.

The third segment 26 (labeled as “C”) is configured to increase theetching resistance and the resist contrast of the exposed region 110 aof the resist layer 110. The third segment 26 (labeled as “C”) includeshydrophobic part or hydrophilic part. The hydrophobic part may includesubstituted or unsubstituted linear, branched, or cyclic hydrocarbongroup, and/or at least one hydrogen of the unsubstituted linear,branched, or cyclic hydrocarbon group is substituted by halogen,hydroxyl, sulfo or carboxyl. The hydrophilic part may include carboxylgroup or silxane group. In some embodiments, the third segment 26 ishydrocarbon group.

In some embodiments, the first post treatment coating material 120includes formula (I), formula (II) or formula (III) as followings. Inthe formula (I), the first post treatment coating material 120 includesthe first segment 22 and the second segment 24. In the formula (II) and(III), the first post treatment coating material 120 includes firstsegment 22, the second segment 24 and the third segment 26.

Next, as shown in FIG. 1F, a portion of the first post treatment coatingmaterial 120 is removed by performing a second develop process, inaccordance with some embodiments. A second developer is used in thesecond develop process. As a result, another portion of the first posttreatment coating material 120 is left on the top surface and sidewallsurfaces of the exposed region 110 a of the resist layer 110. In someembodiments, the second developer is different from the first developer.In some embodiments, the second developer includes polar solvent (suchas water, IPA, methyl isobutyl carbinol (MIBC), alcohol) or organicsolvent (such as PGMEA (propylene glycol monomethyl ether acetate) orPGME (propylene glycol monomethyl ether).

Since there is a physical bond or a chemical bond between the exposedregion 110 a of the resist layer and the first segment 22, a thin filmis formed and left on the top surface and sidewall surfaces of theexposed region 110 a of the resist layer 110. In some embodiments, theremaining first post treatment coating material 120 has a thickness in arange from about 0.1 nm to about 5 nm. As a result, a patterned resistlayer 110 a is formed as illustrated in FIG. 1F.

Afterwards, as shown in FIG. 1G, the middle layer 108 is patterned byusing the patterned resist layer 110 a as a mask to form a patternedmiddle layer 108 a, in accordance with some embodiments.

In some embodiments, the patterned resist layer 110 a is removed. Insome embodiments, the patterned resist layer 110 a is removed by a wetetching process using a polar solvent. The exposed region 110 a of theresist layer 110 become hydrophic since ALG 40 is released from thepolymer 30 to form carboxylic acid group (shown in FIG. 2D). Therefore,the exposed region 110 a of the resist layer 110 is removed by the polarsolvent.

Next, as shown in FIG. 1H, a portion of the bottom layer 106 is removedby using the patterned middle layer 108 a as a mask to form a patternedbottom layer 106 a, in accordance with some embodiments of thedisclosure. As a result, the pattern of the patterned middle layer 108 ais transferred to the bottom layer 106.

Next, as shown in FIG. 1I, an etching process is performed on thematerial layer 104 by using the patterned middle layer 108 a and thepatterned bottom layer 106 a as a mask, in accordance with someembodiments of the disclosure.

Although the voids 112 are formed in the exposed region 110 a of theresist layer 110, the voids 112 are filled with the first post treatmentcoating material 120 to prevent the pattern of resist layer 110 fromcollapsing. In addition, the outer sidewall surfaces and the top surfaceof the exposed region 110 a of the resist layer 110 is covered by thefirst post treatment coating material 120 to improve the line widthroughness (LWR). Therefore, the lithography resolution is improved.Furthermore, the first post treatment coating material 120 is configuredto increase the etching resistance of the resist layer 110 duringpatterning the underlying layers which are below the resist layer 110.

FIGS. 3A-3H show cross-sectional representations of various stages ofperforming a photolithography process, in accordance with someembodiments of the disclosure.

As shown in FIG. 3A, the mask 10 is formed over the resist layer 110,and the exposure process 12 is performed on the resist layer 110, inaccordance with some embodiments of the disclosure.

Next, as shown in FIG. 3B, after the exposure process 12, the exposedregion 110 a and the unexposed region 110 b are formed, in accordancewith some embodiments of the disclosure. Afterwards, thepost-exposure-baking (PEB) process is performed on the resist layer 110.Some voids 112 are formed in the exposed region 110 a since the ALG isreleased from the polymer of the resist layer 110.

Afterwards, as shown in FIG. 3C, the first post treatment coatingmaterial 120 is formed in the voids 112, and over the surfaces of theexposed region 110 a and unexposed region 110 b of the resist layer 110,in accordance with some embodiments.

Next, as shown in FIG. 3D, a portion of the first post treatment coatingmaterial 120 is removed by a first develop process with a firstdeveloper, in accordance with some embodiments. As a result, anotherportion of the first post treatment coating material 120 is remaining onthe surfaces of the surfaces of the exposed region 110 a and unexposedregion 110 b of the resist layer 110 to form a thin film.

As shown in FIG. 3E, the unexposed region 110 b and a portion of thefirst post treatment coating material 120 formed above the unexposedregion 110 b are developed by a second develop process with a seconddeveloper, in accordance with some embodiments. In some embodiments, thesecond developer is different from the first developer. As a result, apatterned resist layer 110 a is formed.

FIG. 3E′ shows a cross-sectional representation of the exposed region110 a of the resist layer 110, in accordance with some embodiments ofthe disclosure. The voids 112 are formed in the resist layer 110 and onouter sidewall surfaces of the resist layer 110. The voids 112 formed onthe outer sidewall surfaces of the resist layer 110 are filled with thefirst post treatment coating material 120, and therefore the outersurface roughness of the resist layer 110 is improved.

Next, as shown in FIG. 3F, the middle layer 108 is patterned by usingthe patterned resist layer 110 a as a mask to form a patterned middlelayer 108 a, in accordance with some embodiments.

In some embodiments, the patterned resist layer 110 a is removed. Insome embodiments, the patterned resist layer 110 a is removed by a wetetching process or a dry etching process.

Next, as shown in FIG. 3G, a portion of the bottom layer 106 is removedby using the patterned middle layer 108 a as a mask to form a patternedbottom layer 106 a, in accordance with some embodiments of thedisclosure. As a result, the pattern of the patterned middle layer 108 ais transferred to the bottom layer 106.

Next, as shown in FIG. 3H, an ion implantation process 14 is performedon the material layer 104 by using the patterned middle layer 108 a andthe patterned bottom layer 106 a as a mask, in accordance with someembodiments of the disclosure. As a result, a portion of the materiallayer 104 is doped to form a doped region 105 in the material layer 104.The doped region may be doped with p-type dopants, such as boron or BF₂,and/or n-type dopants, such as phosphorus (P) or arsenic (As).

In the first embodiments, the unexposed region 110 b is removed beforeforming the first post treatment coating material 120 in the voids 120.In the second embodiments, the voids 112 are filled with the first posttreatment coating material 120 before removing the unexposed region 110b. Compared with the first embodiment, the pattern of the resist layer110 is firstly repaired to further prevent pattern collapse in thesecond embodiment. The line width roughness (LWR) of the pattern of theresist layer is improved by filling the first post treatment coatingmaterial 120 in the voids 112. Therefore, the lithography resolution isimproved.

FIGS. 4A-4G show cross-sectional representations of various stages ofperforming a photolithography process, in accordance with someembodiments of the disclosure.

As shown in FIG. 4A, the mask 10 is formed over the resist layer 110,and the exposure process 12 is performed on the resist layer 110, inaccordance with some embodiments of the disclosure.

Next, as shown in FIG. 4B, after the exposure process 12, the exposedregion 110 a and the unexposed region 110 b are formed, in accordancewith some embodiments of the disclosure. More specifically, theunexposed region 110 b is between a first exposed region 110 a and asecond exposed region 110 a. Afterwards, the post-exposure-baking (PEB)process is performed on the resist layer 110. Some voids 112 are formedin the exposed region 110 a since the ALG is released from the polymerof the resist layer 110.

Afterwards, as shown in FIG. 4C, the first post treatment coatingmaterial 120 is formed in the voids 112, and over the top surfaces ofthe exposed region 110 a and unexposed region 110 b of the resist layer110, in accordance with some embodiments.

Next, as shown in FIG. 4D, a portion of the first post treatment coatingmaterial 120 is removed by a first develop process with a firstdeveloper, in accordance with some embodiments. As a result, anotherportion of the first post treatment coating material 120 is remaining onthe surfaces of the surfaces of the exposed region 110 a and unexposedregion 110 b of the resist layer 110 to form a thin film. The thin filmis left on the top surface of the exposed region 110 a and the topsurface of the unexposed region 110 b by a physical interaction or achemical bonding.

As shown in FIG. 4E, the unexposed region 110 b and a portion of thefirst post treatment coating material 120 formed above the unexposedregion 110 b are developed by a second develop process with a seconddeveloper, in accordance with some embodiments. As a result, a patternedresist layer 110 a is formed.

Next, as shown in FIG. 4F, a second post treatment coating material 130is formed over the first post treatment coating material 120 and overthe middle layer 108, in accordance with some embodiments. The secondpost treatment coating material 130 is used to further repair thesurface roughness of the exposed region 110 a of the resist layer 110.

Afterwards, as shown in FIG. 4G, a portion of the second post treatmentcoating material 130 is removed by a third develop process with a thirddeveloper, in accordance with some embodiments. As a result, thesidewall surfaces of the exposed region 110 a of the resist layer 110are covered by the second post treatment coating material 130. Theremaining second post treatment coating material 130 has a thickness ina range from about 0.1 nm to about 5 nm.

FIG. 4G′ shows cross-sectional representations of the exposed region 110a of the resist layer 110, in accordance with some embodiments of thedisclosure. The voids 112 are formed in the resist layer 110 and onsidewall surfaces of the resist layer 110. The voids 112 formed on thesidewall surfaces of the resist layer 110 is filled with the first posttreatment coating material 120, and the second post treatment coatingmaterial 130 is formed over the first post treatment coating material120. It should be noted that the second post treatment coating material130 is formed over sidewall surfaces of the exposed region 110 a of theresist layer 110, but is not formed over the top surface of the exposedregion 110 a of the resist layer 110 since a thin film made of the firstpost treatment coating material 120 is already formed on the topsurface.

The second post treatment coating material 130 is formed on outersidewall surfaces of the first post treatment coating material 120 tofurther repair the surface roughness. Therefore, the line widthroughness (LWR) of the pattern of the resist layer 110 is improved byusing the first post treatment coating material 120 and the second posttreatment coating material 130. Therefore, the lithography resolution isimproved.

Embodiments for performing a photolithography process are provided. Atri-layer photoresist layer is formed over a material layer over asubstrate. The tri-layer photoresist layer includes a bottom layer, amiddle layer and a resist layer. The tri-layer photoresist layer is usedto pattern the underlying material layer and then is removed. The resistlayer is exposed to a radiation to form an exposed region and anunexposed region. Afterwards, some voids are formed in the exposedregion when a baking process is performed on the resist layer. A firstpost treatment coating material is formed in the voids to repair thepattern of the resist layer and prevent the pattern collapse. The linewidth roughness (LWR) of the pattern of the resist layer is improved andtherefore the lithography resolution is improved.

In some embodiments, a method for performing a photolithography processis provided. The method includes forming a resist layer over a substrateand exposing a portion of the resist layer to form an exposed region andan unexposed region by performing an exposure process. The methodincludes performing a baking process on the resist layer, so that voidsare formed in the exposed region of the resist layer. The method alsoincludes removing the unexposed region of the resist layer to form arecess in the resist layer by performing a first develop process andfilling a post treatment coating material in the recess and the void,and over the exposed region of the resist layer. The method furtherincludes removing a portion of the post treatment coating material byperforming a second develop process, and another portion of the posttreatment coating material is left on surfaces of the exposed region ofthe resist layer to form a patterned resist layer.

In some embodiments, a method for performing a photolithography processis provided. The method includes forming a resist layer over a substrateand exposing a portion of the resist layer to form a first exposedregion, a second exposed region and an unexposed region between thefirst exposed region and the second exposed region. The method alsoincludes performing a baking process on the resist layer, so that voidsare formed in the first exposed region and the second exposed region.The method further includes forming a post treatment coating materialover the first exposed region, the second exposed region, an unexposedregion and in the voids and removing a portion of the post treatmentcoating material by a first developer. The another portion of the posttreatment coating material is left on the top surface the first exposedregion, the top surface of the second exposed region, and the topsurface of the unexposed region. The method includes removing theunexposed region using a second developer, and another portion of thepost treatment coating material is left on the top surface of the firstexposed region and the top surface of the second exposed region.

In some embodiments, a method for performing a photolithography processis provided. The method includes forming a resist layer over asubstrate, and the resist layer includes a polymer and an acid labilegroup (ALG) linked to the polymer. The method includes exposing aportion of the resist layer to form an exposed region and an unexposedregion and performing a baking process on the resist layer, so that theacid labile group cleaves from the polymer to form voids in the exposedregion. The method also includes forming a first post treatment coatingmaterial over the exposed region and an unexposed region, and in thevoids and removing a portion of the first post treatment coatingmaterial. Another portion of the first post treatment coating materialis left on the top surface the exposed region and the top surface of theunexposed region. The method also includes removing the unexposedregion, wherein another portion of the first post treatment coatingmaterial is left on the top surface of the exposed region.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method for performing a photolithographyprocess, comprising: forming a resist layer over a substrate; exposing aportion of the resist layer to form an exposed region and an unexposedregion by performing an exposure process; performing a baking process onthe resist layer, so that voids are formed in the exposed region of theresist layer; filling the void with a post treatment coating material,wherein the post treatment coating material is over the exposed regionof the resist layer; and removing a portion of the post treatmentcoating material, wherein another portion of the post treatment coatingmaterial is left on surfaces of the exposed region of the resist layerto form a patterned resist layer.
 2. The method for performing thephotolithography process as claimed in claim 1, wherein the anotherportion of the post treatment coating material is left on a top surfaceand sidewall surfaces of the exposed region of the resist layer.
 3. Themethod for performing the photolithography process as claimed in claim1, wherein the post treatment coating material comprises a first segmentand a second segment linked to the first segment, and the first segmentis configured to form a physical bond or a chemical bond with theexposed region of the resist layer.
 4. The method for performing thephotolithography process as claimed in claim 3, wherein the firstsegment comprises a halogen atom, hydroxy group, amine group, sulfogroup, or carboxyl group.
 5. The method for performing thephotolithography process as claimed in claim 3, wherein the secondsegment is configured to increase the etching resistance of the posttreatment coating material, and the second segment comprises substitutedor unsubstituted linear, branched, or cyclic hydrocarbon group, orsubstituted or unsubstituted aromatic group, and/or at least onehydrogen of the unsubstituted linear, branched, or cyclic hydrocarbongroup is substituted by halogen, hydroxyl, sulfo or carboxyl.
 6. Themethod for performing the photolithography process as claimed in claim3, wherein the post treatment coating material further comprises a thirdsegment, and the third segment is configured to increase the resistcontrast of the exposed region of the resist layer.
 7. The method forperforming the photolithography process as claimed in claim 1, furthercomprising: performing a post treatment process onto the post treatmentcoating material before removing the portion of the post treatmentcoating material.
 8. The method for performing the photolithographyprocess as claimed in claim 7, wherein the post treatment processcomprises a radiation curing process, a thermal baking process or acombination thereof.
 9. The method for performing the photolithographyprocess as claimed in claim 1, wherein the resist layer comprises apolymer and an acid labile group (ALG), and the ALG cleaves from thepolymer when performing the baking process on the resist layer.
 10. Themethod for performing the photolithography process as claimed in claim9, further comprising: forming a material layer over the substrate;forming a bottom layer over the material layer; forming a middle layerover the bottom layer; forming the resist layer over the middle layer;patterning the middle layer by using the patterned resist layer as amask to form a pattered middle layer; patterning the bottom layer byusing the patterned middle layer as a mask to form a patterned bottomlayer as a mask; and performing an etching process or an ionimplantation process on the material layer by using the patterned bottomlayer as a mask.
 11. A method for performing a photolithography process,comprising: forming a resist layer over a substrate; exposing a portionof the resist layer to form a first exposed region, a second exposedregion and an unexposed region between the first exposed region and thesecond exposed region; performing a baking process on the resist layer,so that voids are formed in the first exposed region and the secondexposed region; forming a post treatment coating material over the firstexposed region, the second exposed region, an unexposed region and inthe voids; removing a portion of the post treatment coating material bya first developer, wherein another portion of the post treatment coatingmaterial is left on a top surface the first exposed region, a topsurface of the second exposed region and a top surface of the unexposedregion; and removing the unexposed region using a second developer,wherein another portion of the post treatment coating material is lefton the top surface of the first exposed region and the top surface ofthe second exposed region.
 12. The method for performing thephotolithography process as claimed in claim 11, wherein the resistlayer comprises a polymer and an acid labile group (ALG), and the acidlabile group cleaves from the polymer when performing the baking processon the resist layer.
 13. The method for performing the photolithographyprocess as claimed in claim 11, further comprising: forming a secondpost treatment coating material over the first exposed region and thesecond exposed region after removing the unexposed region; and removinga portion of the second post treatment coating material, so that anotherportion of the second post treatment coating material is left onsidewall surfaces of the first exposed region and the second exposedregion of the resist layer.
 14. The method for performing thephotolithography process as claimed in claim 11, wherein the firstdeveloper is different from the second developer.
 15. The method forperforming the photolithography process as claimed in claim 11, whereinthe post treatment coating material comprises a first segment and asecond segment linked to the first segment, and the first segment isconfigured to form a physical bond or a chemical bond with the firstexposed region and the second exposed region of the resist layer.
 16. Amethod for performing a photolithography process, comprising: forming aresist layer over a substrate, wherein the resist layer comprises apolymer and an acid labile group (ALG) linked to the polymer; exposing aportion of the resist layer to form an exposed region and an unexposedregion; performing a baking process on the resist layer, so that theacid labile group cleaves from the polymer to form voids in the exposedregion; forming a first post treatment coating material over the exposedregion and an unexposed region, and in the voids; removing a portion ofthe first post treatment coating material, wherein another portion ofthe first post treatment coating material is left on a top surface ofthe exposed region and a top surface of the unexposed region; andremoving the unexposed region, wherein another portion of the first posttreatment coating material is left on the top surface of the exposedregion.
 17. The method for performing the photolithography process asclaimed in claim 16, further comprising: forming a second post treatmentcoating material over the exposed region after removing the unexposedregion; and removing a portion of the second post treatment coatingmaterial to form the second post treatment coating material on sidewallsurfaces of the exposed region of the resist layer.
 18. The method forperforming the photolithography process as claimed in claim 16, whereinthe step of removing the portion of the first post treatment coatingmaterial is performed by a first developer, the step of removing theunexposed region is performed by a second developer, and the firstdeveloper is different from the second developer.
 19. The method forperforming the photolithography process as claimed in claim 16, whereinthe voids are formed on outer sidewall surfaces of the exposed region,and the outer sidewall surfaces of the exposed region are covered by thefirst post treatment coating material.
 20. The method for performing thephotolithography process as claimed in claim 16, wherein the first posttreatment coating material comprises a first segment and a secondsegment linked to the first segment, and the first segment is configuredto form a physical bond or a chemical bond with the exposed region ofthe resist layer.